Osteosarcoma is one of the common malignancies affecting young adults. The most common sites are the femur (42%, with 75% of tumours in the distal femur). A pathological fracture in an osteosarcoma is rare with an incidence, either at diagnosis or during the pre-operative treatment of 5-10%. A 20-year-old male complained of swelling in lower end of right femur since one year. The swelling was insidious in onset and progressive in nature. Patient complained of pain at the site of swelling with significant increase in the size of swelling for past one month. There was no history of trauma and evidence of Café-au-lait spots or other signs of neurofibromatosis. Radiograph of right femur revealed wide zone of transition, cortical destruction, perpendicular and aggressive periosteal reaction and soft tissue involvement at the distal of right femur. Pathological fracture was noted at metaphysis of distal femur. Reconstructed CT image of right femur showed evidence of chondroid and osteoid matrix in the posterior aspect of distal femur. No intramedullary extension was noted. Later wide excision was performed and histopathology examination revealed findings of consistent with periosteal osteosarcoma. Here we present a rare case of periosteal osteosarcoma with pathological fracture at metaphysis of distal femur.